1. Field of the Invention
This invention relates generally to user powered machines, that is machines of the class which are powered by forces exerted by the machine user or operator to drive a movable driven member. The invention relates more particularly to novel machines of the class described which may be constructed and arranged for use as either a vehicular conveyance for the machine user or a stationary exercise machine and whose operation provides an effective therapeutic exercise for certain orthopedic problems, particularly spine and leg problems. The invention relates also to a novel drive system for the machines and other uses.
2. Prior Art
Over the years, a wide variety of user powered machines of the general class described, i.e. exercise machines and user powered vehicles, have been devised. User powered vehicles include land, water, and, just recently, air vehicles. The present invention is concerned with machines of this kind which, broadly stated, are characterized by (a) user actuated means, such as foot actuated pedals or arm actuated members, on which the machine user exerts forces to move the actuated means in a certain machine operating or driving motion, (b) rotary driven means, and (c) a mechanical power transmission means connecting the user actuated means and the driven means in such a way that movement of the user actuated means by the machine user drives the driven means in rotation. The driven means of user powered vehicles are vehicle propelling or driving members, such as drive wheels in the case of land vehicles and propellers in the case of water and air vehicles. In the case of exercise machines, the driven means is a rotor or the like whose rotation is resisted in some way to resist movement of the user actuated means by the machine user.
Among the user powered vehicles of this kind are bicycles, other types of wheeled vehicles including small cars for children, boats, and, more recently, a lightweight airplane. In many of these vehicles, and most notably bicycles, the user actuated means are pedals rotatably mounted on a rotary crank, and the mechanical power transmission comprises a sprocket chain trained about a drive sprocket on the crank and a driven sprocket coupled to the driven vehicle propelling means. Rotation of the crank by the vehicle user drives the propelling means in rotation to propel the vehicle. The transmission may have sprockets of different diameters and shift means for shifting the sprocket chain between these different sized sprockets to vary the drive ratio of the transmission. The pedals are offset along and 180 degrees about the shaft axis so that each pedal is rotatable through a power stroke, comprising about one half of each crank revolution, by the force of the user's foot on the pedal and through a return stroke, comprising the remainder of each crank revolution, by the force of the user's other foot against the other pedal.
In other pedal driven vehicles, such as small pedal driven cars for children, the pedals are movable back and forth with a generally reciprocatory motion longitudinally of the vehicle. The pedals are drivably connected to the vehicle propelling means by a mechanical power transmission including connecting rods pivotally attached to the pedals and to crank portions of a driven shaft drivably coupled to the vehicle drive wheels. These crank portions are offset along and 180 degrees about the shaft axis so that reciprocatory movement of the pedals drives the shaft in rotation to propel the vehicle. Each pedal is movable through a power stroke in one longitudinal direction of the vehicle by the force of the user's foot against the pedal and through an opposite return stroke by the force of the user's other foot against the other pedal.
While all of the existing user powered vehicles of the class described are satisfactory for their intended purposes, most if not all are designed for recreational and/or transportation use only by relatively strong, healthy, agile persons. As a consequence, the vehicles have certain features which render the vehicles difficult or impossible to use by many persons, such as persons having less than average agility or strength or persons who suffer from certain orthopedic problems. These features also render the vehicles unsuitable for optional use as therapeutic exercise machines for treating certain leg and other orthopedic problems.
Among the foremost of these features are the following. The pedals of the existing pedal driven vehicles are interconnected in a way which requires the pedals to always undergo their full vehicle propelling motion in unison but 180 degree out of phase. Each pedal is driven through each of its full power strokes by the vehicle user simultaneously with movement of the other pedal through its full return stroke. As a consequence, both legs of the user must always be used to operate the vehicles, and the user can exert a vehicle driving force against only one pedal at a time. Moreover, pedals mounted on a rotary crank have two diametrically opposed dead center positions relative to the position occupied by the vehicle user. If the pedals initially occupy these dead center positions when the vehicle is at rest, it is very difficult and often impossible to commence rotation of the pedals unless they are first moved in some way from such positions. This movement of the pedals from a dead center position is most difficult for those who have less agility or strength than average or who suffer from leg and various other orthopedic problems.
Other features of the existing pedal driven vehicles make these vehicles unsuitable for use as therapeutic exercise machines for exercising persons with certain leg, spinal, and other orthopedic problems. One such feature resides in the fact that the user leg extension and retraction movements and distances required to operate the vehicles are fixed by the fixed diameter of the circular path of pedals mounted on a rotary crank, such as bicycle pedals, and the fixed stroke length of reciprocatory pedals. In the case of bicycles, additional features which make them unsuitable for use by less agile persons and for exercising persons with many leg, spinal, and other therapeutic problems are balance, the location of the seat almost directly over the pedals, the generally upright position of the bicycle rider, and the generally vertical direction of the rider's leg movements. Such rider body orientation and leg motion are either not the most efficient for or are totally unsuitable for many orthopedic problems which can be effectively treated and alleviated by appropriate pedaling type exercises.
A variety of stationary exercise machines of the class defined by (a), (b), (c) above have also been devised. Except for the "vehicle" characteristics or features of the user powered vehicles discussed above, the existing exercise machines of the class described are quite similar to such vehicles and possess many if not most of the other features just discussed. As a consequence, many if not all of these existing exercise machines are not suitable for the therapeutic exercise uses discussed above.